This invention relates to electrostatographic xerographic type reproduction machines, and more particularly, to an improved control system for such machines.
The advent of higher speed and more complex copiers and reproduction machines has brought with it a corresponding increase in the complexity in the machine control wiring and logic. While this complexity manifests itself in many ways, perhaps the most onerous involves the inflexibility of the typical control logic/wiring systems. For as can be appreciated, simple unsophisticated machines with relatively simple control logic and wiring can be altered and modified easily to incorporate changes, retrofits, and the like. Servicing and repair of the control logic is also fairly simple. On the other hand, some modern high speed machines, which often include sorters, a document handler, choice of copy size, multiple paper trays, jam protection and the like have extremely complex logic systems making even the most minor changes and improvements in the control logic difficult, expensive and time consuming. And servicing or repairing the machine control logic may similarly entail substantial difficulty, time and expense.
To mitigate problems of the type alluded to, a programmable controller may be used, enabling changes and improvements in the machine operation to be made through the expediency of reprogramming the controller. However, the control data which operates the machine and which is stored in the controller memory pending use, must be transferred to the various machine components at the proper time and in the correct sequence without unduly interfering with or intruding unnecessarily upon the other essential functions and operations of the controller.
Unfortunately, as the complexity of these high speed reproduction machines increase, so does the potential for malfunctions. The present invention is especially concerned with mitigating downtime by incorporating built-in diagnostic programs in the controller which directs the operation of the machine components. The automatic document handler is an extremely intricate device which must be exactly synchronized with the machine processor. Accordingly, some of these diagnostic programs are directed towards checking the operation of the document handler.